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VOLUME 58 , ISSUE 4 ( October-December, 2016 ) > List of Articles


Step AFB Technique: A Simple Method for Increasing AFB Yield in Tissues

Gayathri P. Amonkar, Manish Gaikwad, Heena M. Desai

Keywords : Tissue, AFB, Step AFB

Citation Information : Amonkar GP, Gaikwad M, Desai HM. Step AFB Technique: A Simple Method for Increasing AFB Yield in Tissues. Indian J Chest Dis Allied Sci 2016; 58 (4):273-274.

DOI: 10.5005/ijcdas-58-4-273

License: CC BY-NC 4.0

Published Online: 18-11-2022

Copyright Statement:  Copyright © 2016; The Author(s).


The yield of acid-fast bacillus (AFB) in tissues is usually low in conventional formalin fixed tissues. We carried out a simple technique to increase the chances of AFB detection in tissue sections. AFB staining was done on the lung tissue of 100 consecutive autopsy lung specimens of pulmonary tuberculosis over a period of three years. In addition, we carried out the step AFB technique in which the AFB procedure was carried out after 10 serial re-cuts in all the cases. AFB appeared as pink/red in a blue background. Grading was done as negative, 1+, 2+ and 3+. AFB positivity was observed in 55% cases with the first tissue cut. However, step AFB technique increased the tissue AFB positivity yield to 66% (p=0.002). The remaining 34% cases were negative for both AFB and step AFB. Grade I positivity was observed in 91% cases, Grade 2 in 6% and Grade 3 in 3%. The results show a better edge for picking up AFB with step AFB technique as compared with the conventional method that could be attributed to the greater concentration of TB bacilli in deeper part of the tissue, hence decreasing the chance of obtaining false negative results. We conclude that Step AFB technique can be used as an adjunct to routine AFB technique to increase the chances of obtaining a positive result.

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